Carpet sweeper wheel linkage



Oct. 14, 1 952 I p HEFTLER CARPET SWEEPER WHEEL LINKAGE 2 SHEETS-SHEET 1Filed April 23, 41946 FIG. 5

Pouyws PRESSURE OF BRUSH ON FLOOR Oct. 14, 1952 P. HEFTLER I 2,613,380

CARPET SWEEPER WHEEL LINKAGE Filed April 23, 1946 v .2 SHEETS-SHEET 2 Fl G 7 S 52. 58d 42 I 46 41 42 s Q W 48 FIG-8 lee FIGIO Patented Oct. 14,1952 UNITED STATES PATENT OFFICE.

CARPET SWEEPER WHEEL LINKAGE Paul Heftler, Windsor, Ontario, CanadaApplication April23, 1946, Serial No. 664,390

' The" devices described here andshown in the accompanying drawings arecarpet sweepers which automatically adjust themselves to-the thicknessorsoftness of the rug on which they may happen to be used. They sweepany floor or floor covering, from bare wood or linoleum to the softestand thickest of chenille rugs, without it being necessary to beardown-at all on the handle. In fact, they will sweep these surfaces andgo from one to the other, adjust ing themselves as they go, with theirhandles removed and being ulled along by a strin Besides beingself-adjusting, these sweepers are very'responsive to" pressure ap liedto them by their handles. Thus; when the erson using one of thesesweepers wants the sweeper to sweep with more ower, so as to pick up"some stubborn dirt, the sweeper needs less pressure on itshandie thanany earlier design of carpet sweeper.

Two of the best forms of these sweepers are shown in the drawing. Figure1 is an end view of the first form, with one wheel and parts oi the endiron broken away; and Figures 3" and 4 are sections taken on the lines2-4; 3-? and 4-4 in Figure I; Figure 5" is a graph that is referred tolater in explaining the operation of the sweeper. Figure 6 is an endviewof the second form or model, and Figure 7' is aview like Figure 6 butwith the handle bail, bumper cord and most of the end cover removed toshow the mechanism within. Figures 8; 9 and 10 are sections on aslightly larger scale taken on the lines 8-4, 9 9 and Ill-40 in Figure6'.

The first form of the new swee er, shown in Figures 1 to 4, is made witha conventional case I havinga simple end bar 2 extending across each endto carry a bush pivot 3- and support a bumper t; The brush pivot alsoacts as a rivet to hold a bumper clip 5 on the-end bar. These arts,as-well asthe brush 6, brush pulley 1, axles 8,- axle tubes 9, dustpansin and the mechanism for dumping the dust pans are similar to" orare the'sairie as those of} sweepers now on the market.

The wheels H are of the common ball-bearmg". type shown in the Mason andShanahan Patent-No. 877,852, but they are mounted inside out as comparedwith the usual arrangement so that the ball bearing is on the inner sidetowardsthe case. Eachwheel ll has-a rubber tire l2. cemented to its-rim;and it is riveted to the outer: end of a hub 13. The fastening of thewheelt'o its hub is made more rigid by a thick washer M placed-on thehub against the'wheel before: the end: orthe hub is riveted down. The

hub I3 is drilled part way through from its in ner end to take the endof the axle 8,- and the outside-of the hub is made with a groove whichacts as a raceway for the balls IS. The other raceway is formed by apairofstampings i6 that are held together by a flange on one of thembeing clenched over aflange on the other. The stampings 16 have radialarms lta that lie together and act as a link by which the wheel isconnected to" the rest of the mechanism of the sweeper.

The axles 8" serve chiefly to hold the wheels iri-lifie and to limittheir movement to what ispermitted by the clearance around the axlesihthe axle" tubes 9; The axles also serve to hold the wheels againstmoving in against the sides of" the case; but to make sure that the endsof the hubs do not catch in theends of the axle tubes; thin metalwashersH are pro vided on the axles between the wheels and the case. The wheelsare prevented from moving toofar out away from" the case by the end bar2, against which theouter ends of the hubs [3 will come as soon as thewheelsmove out a fraction of an inch from their proper positions.

The wheel bearing arms or links 16d are connected to the. case through ayoke 18 mounted on the end of the case so that it can slide up anddowiiwith the wheels. The yoke It isa metal plate, and the connectionsbetween it and the bearing arm l6'a are formed by lugs or fin gers umbent up from the edgeof theyokeand extending straight out through holesin the ends of the links [6a. The ends of the lugs" that go through thelinks curve down and in away from the centers of the wheels so as toprevent any accidental slidingof the links 01? the lugs. The lugsareplaced on theyoke lose that the'links Ilia slope down and in towardseach other at angles to the vertical; these angles being aboutforty-five degrees so that any forces transmitted to the wheels throughthe links 16a will make the wheels press against the brush pulley 1 justas names it makes them press down on the floor or rug- 19.

The bottom of theyoke l8 is'gui'ded in its upand-down movementsbya pairof round headed screws 20 that pass through slots 2'! in the yoke and:into the end of the case, and the top ofthe yoke is guided by a lever:22 pivoted at one" end to the case and at the other end to the yoke. Thepivot 23 between the lever and the yoke is a shoulder rivet, and thepivot or fulcrum at the. other end of the lever is a stepped collar 24fixed to the case by a screw 25', the head. of

3 the screw being big enough to keep the lever from sliding oiT thecollar or sleeve 24.

Each of the two yokes it, one at each end of the sweeper, is providedwith two springs 26 which tend to lift the case and push down the yoke.These springs are of the hairpin type and are made with several coilsconnecting the two arms, which extend out at a considerable angle toeach other and have loops at their ends. One end loop of each spring ispivoted to the case by a screw 21 driven into the case, and the otherend loop is pivoted on an eye or hook [8b on the bottom of the yoke, thetwo pivots allowing the spring to work with very little friction.

The lever 22 that connects the top of the yoke 18 to the case alsoconnects the handle of the sweeper to the case and to the wheels. Thehandle is made with the usual handle bail 28, that has, at each end, apivot 29 riveted to it and projecting in towards the case. The pivotZQ-flts into a hole in the lever 22 which forms a bearing for it, sothat the only connection between the handle and the case is through thelevers 22 (one at each end of the sweeper). The pivot 29 extends alsothrough a slot 30 in the yoke and into a hole 3| in the end of the case,but these are large enough so that the pivot never touches either theyoke or the case and acts only on the lever. The extra length of thepivot is merely to keep it from accidentally coming ut of its pivot holein the lever.

To hold the sweeper handle up when the sweeper is not in use, the upperedge of the yoke is formed into a flange H30 having a notch lBd betweentwo parts that project out into the path of the handle bail 28. As thebail is swung up straight, its legs spring over the projections lBc andthen snap into the notches Hid at each end of the sweeper and hold thehandle up.

Down to this point, this description of the sweeper has included onlythose things that might be seen from the drawing. But the most importantthings about this sweeper are not so easy to see; they are describedbelow.

The first of these things is the strength of the springs 26. They arevery flexible, several times as flexible as the springs ordinarily usedon carpet sweepers, and they are not strong enough to lift the brush,weighted down by the case, off the floor. In more technical terms, therate of the springs is very low, and the force exerted by the springs isless than the sprung weight of the sweeper.

The flexibility or low rate of the springs is secured partly by makingthem of fine wire and providing a considerable length of wire in thecoiled parts of the springs and partly by the shape of the springs. Mostof the springiness of each spring is in the coils because the forcesthat act on the springs have more leverage on the wire in the coils thanon the wire in the arms. The leverage under which the coils work isequal to the distance from the coils to a line drawn between the ends ofthe arms. This distance increases as the arms of the spring cometogether, and the increase in this distance and the leverage off-setsmost or all of the increase in the forces exerted by the wire in thecoils of the spring as the spring is bent. In fact, if the springs aremade so as to be as shown in the drawing when they are in use and tohave their arms extending straight out in opposite directions when theyare free, the effective rate of the springs will be practically zero.

What the force exerted by the springs should be depends on the weightsof the various parts of the sweeper, the torque needed to turn the brushwhen it is pressing on the carpet, the diameter of the brush, and thediameter of the brush pulley. In this particular sweeper, whose totalweight is six pounds, the weight is distributed as follows:

Pounds Case and parts moving up and down with it,

such as brush, end bars, bumper, dust pans, and half of springs andlevers 35 Wheels and parts moving up and down with them, such as axles,bearings, yokes, and

half of springs and levers 1.1 Lower end of handle and bail resting onthe handle pivots 0.9 Upper end of handle and bail resting in the handof the person using the sweeper 0.5

Total 6.0

The 0.5 lb. of the handle and bail that rests in the hand has not-effecton the working of the sweeper. The 0.9 lb. of the handle and bail thatrests on the levers 22 is applied by them to the case and to the yokes,one-third of this weight or 0.3 lb. to the case and two-thirds or 0.6lb. to the yokes and through them to the wheels. The total weight movingup and down with the case is therefore 3.5 lbs. plus 0.3 lb. or 3.8 lbs.This is called the sprung weight because it rests on the springs. Thetotal weight carried directly by the wheels and not through the springsis 1.1 lbs. plus 0.6 lb. or 1.7 lbs. This is called the unsprung weight"because none of it is carried by the springs.

The diameter of the spring wire and the size and number of coils in eachspring is such that the four springs acting together exert a liftingforce of 2.9 lbs. on the case. This is 0.9 lb. less than the sprungweight. In order words, the springs are too weak by 0.9 lb. to hold upthe case and the parts that move up and down with it. The result isthat, whenever the sweeper is set on a floor or rug and rolled along andno matter whether the floor is bare or the rug is thick and soft, thecase will sink down until the brush rests on the floor or rug with apressure of 0.9 lb. The rest of the weight of the sweeper on the flooror rug will be carried by the wheels and will make them press on thefloor or rug with the pressure of 4.6 lbs.

When the brush is bearing down on the floor or rug with a pressure of0.9 lb. it is bearing down hard enough for ordinary sweeping. When thewheels are bearing down with a pressure of 4.6 lbs., they will haveenough traction to drive the brush when it is bearing down with apressure of 0.9 lb. without there being much slippage. This slippage ispractically nothing on a hard floor and is about 7% with these pressureson an average rug with a good wellbristled brush. Also, when the wheelsare bearing down with a pressure of 4.6 lbs., they are bearing againstthe brush pulley with a pressure that is practically the same as theirpressure on the floor, because of the angles of the links [6a. With thispressure, there is no appreciable slippage between the wheels and thebrush pulleys. Thus, not only does the brush automatically rest with theright pressure on the floor or rug but the wheels will have all thetraction that they need to drive the brush. Therefore, no matter whetherthe sweeper is "-TGh -H. hard fioor or a thitk soft mg, all that itneeds =toma-ke i-tsweep is to be pushed or pulled alongg and there -is.no need to press down on qt "When one wants to make the sweeper sweepwith more power, the natural thing to do .lS to :press:down :on has itis being moved back and forth. The pressure applied to it is ap-"pliedthrough the handle, and this pressure is divided between the-yokes l8 and the case I 'i'by' theulevers 32 2. This division is in theratio :of .ltwoato zoneso that, if the added pressure .is. :33 lbs.,theraddedspressure on the yokes will ibe .212. lbs. j andjtheradded.pressure onthe case :willzbe .1.1;lbs.. These pressures will be passed.on TtD the. wheels :and. the brush, sothat the wheelsiwilhbeardownwitha total pressure :of 1.618 lbs;, rand the thrush .will bear .downwith 'a total pressure of2*.0 .lbs. As before, these pres- ISLIITESonthe floor '01 frugzare correctly balanced;

the pressure of the wheels is enough, :butnot much more than enough, to'get the traction that .15 :needed to ,drive the brush.

The dead-weight ,of the, sweeper is dlvided'be- :tween the wheels.andthe .brush in the .ratio of about dive :to :one, and the pressurecoming through thedoandle is divided in the ratio of two :to one. Theseratios .are .different because the brushdoes not havethe samecoefficient of friction when its is pressing downxhard .as when itispressing down lightly. Ifit had, the torque needed to :drive it wouldbe proportional to its pressure on the .rug. Instead :of this, doublingthe .pressure of :thebrush on "the rug increases the torque .needed todrive it by :much less than double. The .exactrelations between thepressure and the torque are-shown by'the curve in Figure 5, whichshowshow the torqueincreases at aslower and slower .rateas the pressure isincreased.

.ratio of ten to :one, butsuch asweeper would not be takingfulladvantage of the'invention.

Although the sweeper described above and .shown in Figures 1 to 4 isperhaps the best sweeper that has been made, it does have one slightfault; it is not well balanced about its handle pivots. This results inthe front of the sweeper lifting up-a little when the sweeper is ,pushedback and forth very quickly. Also, that sweeper, with its open ends, isnot stylish. To cure thesefaults or defects, the improved model tshowninFigures '6 to has been designed.

The improved sweeper is made with a conventional wooden case 4!, to eachend of which is fastened a rounded metal end cover 42, and

it. is encircled by a rubber bumper band 43 held onin anyconventionalway. Most of the operat- .ing mechanism of the sweeper lies within theend covers, but a handle pivot 44 projects out through a hole 45 in theside of each cover and --.-has one end of the handle :bail 46 pivoted onit.

The'handle bail 4B is in the shape of an inverted .U straddling thesweeper with each of its legs lying close --.against but .not rubbingthe side of the end: :cover. Directlyi-above 'athelhandle ip'ivot,

two bosses 4! are formedii-ni'the end coverssozthat,

when the handle-is swung :upright, the ;bai1.1will ride over one. bossand snap-between the twozand thushold itself upright when the sweeper isnot in use.

The brush "'48, together with iitszpulleys t9, is

mounted on a pivot Bllriveted to a springy brush pivot bracket 5 I.'oneend ona shoulder .rivet 52 fixed .to the end The bracket :51 ispivoted "at eend cover :42, asv shown in :Fig. .3. Except when the.brushis to be removed, the hook 53 andxthe shoulder 54 hold the bracket.51 from. moving .either up :or down, :and. thus the brush pivot isordinarily fixed.

The central :part .of rtherbracket 5| is xofisetzlin away from the .endcover and extends down :as

.far as the bottomedge of the aend' cover, which is .cut away alittle to:make the sbracketmore accessible. Toremove the brush, the lower end ofthe bracket 5| is pressed in .far enoughto spring .the bracket :offtheshoulder .54,and .the

end of the brush held by the bracket .isipulled out of the case, :thebracket swinging out with the brush. The same operation isperformed; at

the other endof the brush with theother bracket, and then the twobrackets aresprung apartxfar enough to withdraw first nne pivot 50 fromthe brush and then the other. ,This .isreasy to .do

because the two brackets at the opposite ends of the sweeper swingawayfrom :each other towards opposite sides of the sweeper, :themechanisms on the .two ends of the sweeper being the same and not rightand .left :handed.

The handle pivot 44 is not mounted on any fixed, part of the sweeper but:is carried by aprimary lever 55 carriedby a pivot .56 fixed .to-the endcover at thesame .height as the handle pivot. The other end of thelever55 is connected by a pivot 51 to a yoke 58, which arches over anddown at each side of the brush pulley 45. To make both ends of the :yoke.58, move up and down together as thelever55 moves-up and down, a.secondary lever.59 is mounted-ona fu1 crum (won the end plate and *isconnected by pivots SI and .62 to the primary lever 55 and the yoke.Both of the levers 55 and 59 have a ratio of two to three, the distancesbeingmeasured horizontally, and the piVOt 6| connecting them togetherhas its axis directly above the axis of the handle pivot ,so the ends ofthe levers pivoted to the yoke move up and down the same distance at alltimes, and the yoke moves up and down without tipping.

To ensure smooth operation of thelevers and the yoke, the fulcrum 56 andyoke pivot 57 of the primary lever are in one horizontal plane, thefulcrum 58 and yoke pivot 62 of the secondary lever are in anotherhorizontal plane, and the two fulcrums 5E and 60 and the interconnectingpivot BI are in a third plane. Also, the

fulcrum end of the secondary lever has a slot to receive the fulcrum 5B,which is fixed to the-end cover, and the yoke has a slot to receivethepivot 62, which is fixed to the secondary lever. The places where thelevers are pivoted to eachother or to the yoke are embossed slightly toprevent the parts from rubbing oneach'other and'creating friction .at.other places, and the ,yokewend .of the primary lever and the fulcrumend :of the '7 secondary lever are offset so as to lie against the partsto which they are pivoted.

The primary lever 55 is F-shaped, so that its body will not interferewith the brush pivot bracket i or the hook 53 into which the bracketfits, both ends of the bracket and the hook lying in approximately thesame plane as the lever. The central arm of the primary lever, whichcarries the handle pivot 44, extends down between the offset centralpart of the bracket 5| and the end cover 42, as shown in Figure 9, andit is long enough to cover up the back of the hole 45 in the end coverthrough which the pivot projects. It is also formed with a boss, onwhich the handle pivot 14 is mounted, high enough to project through thehole ife in the end cover and to prevent the handle ball 6 from rubbingon the end cover.

The lower ends of the yoke 58 are connected to th wheels 63 through thebanjo bearings 64, each end of the yoke having a finger 58a bent in fromthe body of the yoke and extending through a hole in the end of thebanjo bearing arm. The banjo bearings 64, the wheels 63, and

the axles 65 are of the well-known type shown in U. Patent No. 877,852,and the axles 65 extend through axle tubes 66 in the usual manner. Metaland fibre washers 67 and 68 on the axles space the wheels out from theends of the case 4| and prevent dust from entering the axle tubes. Thedust pan 89 may be of any common type.

The major part of the weight of the sweeper is transmitted to the wheels83 by the springs H, one end of each spring engaging a hook l2 stampedout of the end cover 42 and the other end engaging a hook 581) formed onthe lower end of the yoke 58. Thesesprings H work exactly like thesprings 28 in the sweeper shown in Figures 1 to 4, except that thesweeper of Figs. 6 to will be a little heavier and its springs willtherefore be a little stronger. If the second sweeper weighs 0.60 lb.more than the first, the springs It should each exert a force 0.10 lb.more than the springs 26, so that two thirds of the additional weight iscarried by the wheels and one third by the brush.

The sweeper of Figures 8 to 10 operates in the same way, except for theslight difference in weight, as the sweeper of Figures 1 to 4, so thereis no need of explaining at length how it works.

The application for this patent is a continuation-in-part of a forfeitedapplication Ser. No. 394,130 filed on May 19, 1941. Although only twospecific forms 01" th invention are described above, the inventioncovered by this patent is not limited to them but includes any sweeperthat fits any of the following definitions or claims.

I claim:

1. In a carpet sweeper, a case, a brush mounted to turn on a fixed axisin the case and having friction pulleys on its ends outside of the case,four wheels movable up and down with respect to the case, one wheelbeing located on each side of each pulley and arranged to roll on thefloor and against the pulley to drive the brush, end covers outside ofthe pulleys and the wheels, levers lying outside of the pulleys and thewheels and inside of the end covers, each lever being connected at oneend to an end cover and at the other end to a wheel, and a handleconnected to each lever between its ends.

2. In a carpet sweeper having a rotary brush, a friction pulley fixed toone end of the brush, wheels on both sides of the pulley and arranged toroll on the floor and against the pulley to drive the brush, and a framemember extending around outside the pulley and the wheels, a handlepivot carrier extending down between the pulley and the frame member andmovable up and down, a handle pivot on the handle pivot carrier besidethe pulley, mechanism connected to the handle pivot carrier and operatedby it for adjusting the sweeper, a horizontally extending brush pivotbracket having one end pivoted to the frame member and having a partnormally lying between the handle pivot carrier and the end of the brushand carrying a pivot for the brush, the bracket being long enough sothat it can be swung down to carry the brush pivot below the framemember and springy enough so that the brush pivot can then be sprung outof engagement with the brush. and releasable means for holding thebracket in its normal position on the inner side of the frame member.

3. In a carpet sweeper having a case assembly, a rotary brush in thecase assembly, friction pulleys on the ends of the brush, pivots for thebrush fixed to the case assembly, and four wheels movable up and downwith respect to the case assembly and arranged to roll on the floor andagainst the pulleys to drive the brush, a pair of handle pivots that canmove up and down relative to the case assembly, a primary lever at eachend of the sweeper connected to the case assembly at one point and to awheel at another point and to one of the handle pivots at a pointbetween the first two points, and a secondary lever at each end of thesweeper connected to the case assembly at one point and to a wheel atanother point and to the primary lever at a point which is between thefirst two points on the primary lever and between the first two pointson the secondary lever.

4. In a carpet sweeper, wheels for rolling on the floor, a case, a brushprojecting below the case so as to rest on the floor, the case and thebrush being movable up and down with respect to the wheels, springsconnected to the Wheels and the case for transferring a portion of theweight of the case and the brush to the wheels, the springs having onlyenough strength to carry a part of the weight of the case and the brush,the rest of the weight of the case and the brush being carried by thebrush throughout the n0rmal range of movement of the wheels relative tothe case, a handle connected to the sweeper for moving it on the floorand for applying downward pressure to it, and levers on the sweeper fordividing the pressure applied by the handle between the wheels and thebrush in a fixed ratio.

5. In a carpet sweeper, wheels, a brush and other members forming aweight movable up and down with respect to the wheels, springs actingbetween these members and the wheels and strong enough to carry only apart of their weight so that the brush will sink down and bear on thesurface of any floor or carpet on which the sweeper may be placedwithout any downward pressure being applied to the sweeper, a handlethrough which downward pressure may be applied, and a lever mechanismfor receiving downward pressure from the handle and dividing it betweenthe wheels and the brush.

6. In a carpet sweeper, a brush, wheels movable up and down with respectto the brush, dust pans and other members connected to the brush andforming a weight acting to push the brush down, springs constructed andarranged to trans- 9 mit a part but not strong enough to transmit all ofthis Weight and the weight of the brush to the wheels, a handle throughwhich downward pressure can be applied, and levers for dividing thedownward pressur from the handl between the wheels and the brush.

7. In a carpet sweeper, a case assembly, a brush journaled to rotate ona fixed axis in the case assembly, dust pans carried in the caseassembly on both sides of the brush, wheels on both sides of the brushaxis, the wheels being movable up and down with respect to the caseassembly and arranged to roll on the floor and drive the brush,

floor or carpet, means for supporting said brush and said frictionpulleys for free vertica1 movement through a definite range of movementrelative to said wheels, means for dividing the weight of said sweeperbetween said wheels and said brush resting on a floor or carpet in oneratio throughout said range of movement whereby both said wheels andsaid brush can rest freely on said floor or carpet without any pressurebeing applied to said handle no matter whether the 10 floor is hard andsupports said wheels without yielding or whether the carpet is thick andsoft enough to let said wheels sink down in below the level of saidbrush, said means for dividing the weight of the sweeper includingsprings for transmitting a part of the weight to the wheels, and meansfor dividing any pressure applied to said sweeper by said handle betweensaid wheels and said brush in another ratio, said, weight dividing meansand said pressure dividing means being proportioned so that thepercentage of said handle pressure applied to said brush is greater thanthe percentage of said sweeper weight carried by said brush.

PAUL HEFTLER.

REFERENCES CITED The following references are of record. in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 162,520 Beckford Apr. 27, 1875383,806 Gore May 29, 1888 397,102 Wiedersum Jan. 29, 1889 539,445Raymond May 21, 1895 756,042 Murdick Mar. 29, 1904 878,432 Totten Feb,4, 1908 1,012,726 Shanahan Dec. 26, 1911 1,079,694 Deacon Nov. 25, 19132,085,209 Bissell June 29, 1937 2,171,633 Pullen Sept. 5, 1939 2,178,917Pullen Nov. 7, 1939 2,278,736 Poggensee Apr. 7, 1942

